Turbocharger having balance valve, wastegate, and common actuator

ABSTRACT

A turbocharger for a use with a combustion engine is provided. The turbocharger may have a turbine housing with a first volute, a second volute, and a common outlet. The turbocharger may also have a turbine wheel disposed between the common outlet and the first and second volutes. The turbocharger may further have a first valve configured to selectively fluidly communicate the first volute with the second volute upstream of the turbine wheel, a second valve configured to selectively fluidly communicate the second volute with the common outlet to bypass the turbine wheel, and a common actuator configured to move the first and second valves.

TECHNICAL FIELD

The present disclosure is directed to a turbocharger and, moreparticularly, to a turbocharger having a balance valve, a wastegate, andan actuator common to both the balance valve and the wastegate valve.

BACKGROUND

Combustion engines such as diesel engines, gasoline engines, and gaseousfuel-powered engines are supplied with a mixture of air and fuel forcombustion within the engine that generates a mechanical power output.In order to maximize the power output generated by this combustionprocess, the engine is often equipped with a divided exhaust manifold influid communication with a turbocharged air induction system.

The divided exhaust manifold increases engine power by helping topreserve exhaust pulse energy generated by the engine's combustionchambers. Preserving the exhaust pulse energy improves turbochargeroperation, which results in a more efficient use of fuel. In addition,the turbocharged air induction system increases engine power by forcingmore air into the combustion chambers than would otherwise be possible.This increased amount of air allows for enhanced fueling that furtherincreases the power output generated by the engine.

In addition to the goal of maximizing engine power output andefficiency, it is desirable to simultaneously minimize exhaustemissions. That is, combustion engines exhaust a complex mixture of airpollutants as byproducts of the combustion process. And, due toincreased attention on the environment, exhaust emission standards havebecome more stringent. The amount of pollutants emitted to theatmosphere from an engine can be regulated depending on the type ofengine, size of engine, and/or class of engine.

One method that has been implemented by engine manufacturers to complywith the regulation of these exhaust emissions includes utilizing anexhaust gas recirculating (EGR) system. EGR systems operate byrecirculating a portion of the exhaust produced by the engine back tothe intake of the engine to mix with fresh combustion air. The resultingmixture has a lower combustion temperature and, subsequently, produces areduced amount of regulated pollutants.

EGR systems require a certain level of backpressure in the exhaustsystem to push a desired amount of exhaust back to the intake of theengine. And, the backpressure needed for adequate operation of the EGRsystem varies with engine load. Although effective, utilizing exhaustbackpressure to drive EGR can adversely affect engine operation, therebyreducing fuel economy. Thus, a system is required to reduce exhaust backpressure while still providing the necessary EGR flow.

U.S. Pat. No. 6,321,537 to Coleman et al. (“the '537 patent”) disclosesa combustion engine utilizing an EGR system and a divided exhaustmanifold together with a turbocharged air induction system.Specifically, the '537 patent describes an internal combustion enginehaving a plurality of combustion cylinders and an intake manifold incommon fluid communication with the combustion cylinders. A firstexhaust manifold and a second exhaust manifold are separately coupledwith the combustion cylinders. A first variable geometry turbine isassociated with the first exhaust manifold, and a second variablegeometry turbine is associated with the second exhaust manifold. The EGRsystem includes a 3-way valve assembly disposed in fluid communicationbetween the first exhaust manifold, the second exhaust manifold, and theintake manifold. The valve assembly includes an inlet fluidly coupledwith an inlet of the first variable geometry turbine, a first outletfluidly coupled with an inlet of the second variable geometry turbine,and a second outlet fluidly coupled with the intake manifold.

During operation of the combustion engine described in the '537 patent,exhaust flows in parallel from the first exhaust manifold to the firstvariable geometry turbine and from the first exhaust manifold to thevalve assembly. Spent exhaust from the first variable geometry turbineis mixed with exhaust from the second exhaust manifold and fed to thesecond variable geometry turbine. Spent exhaust from the second variablegeometry turbine is discharged to the ambient environment. The valveassembly is selectively actuated to control a flow of exhaust from thetwo outlets. Exhaust flowing from the first outlet mixes with exhaustfrom the second exhaust manifold and flows into the second variablegeometry turbine. Exhaust from the second outlet is cooled and thenmixed with combustion air. The mixture of combustion air and exhaust isthen transported to the inlet manifold. Controlling the amount ofexhaust gas which is transported to the intake manifold provideseffective exhaust gas recirculation within the combustion engine.Moreover, controlling the flow of exhaust to the second variablegeometry turbine utilizes energy from the exhaust which is nottransported to the intake manifold to drive the second variable geometryturbine.

Although the system in the '537 patent may adequately control exhaustgas recirculation in a turbocharged engine, it may be less than optimal.That is, in some situations, the backpressure within the first exhaustmanifold may be excessive. And, without any way to relieve thisbackpressure, damage to the first variable geometry turbocharger may bepossible.

The disclosed turbocharger is directed to overcoming one or more of theproblems set forth above and/or other problems of the prior art.

SUMMARY

In one aspect, the disclosure is directed toward a turbocharger. Theturbocharger may include a turbine housing with a first volute, a secondvolute, and a common outlet. The turbocharger may also include a turbinewheel disposed between the common outlet and the first and secondvolutes. The turbocharger may further include a first valve configuredto selectively fluidly communicate the first volute with the secondvolute upstream of the turbine wheel, a second valve configured toselectively fluidly communicate the second volute with the common outletto bypass the turbine wheel, and a common actuator configured to movethe first and second valves.

In another aspect, the disclosure is directed toward a method ofhandling exhaust from an engine having a first plurality of combustionchambers and a second plurality of combustion chambers. The method mayinclude receiving exhaust from the first plurality of combustionchambers, and receiving exhaust from the second plurality of combustionchambers. The method may also include moving a valve assembly in a firstdirection by a first amount to mix exhaust received from the firstplurality of combustion chambers with exhaust received from the secondplurality of combustion chambers, directing exhaust received from thefirst and second pluralities of combustion chambers through a turbine,and moving the valve assembly in the first direction by a second amountto allow exhaust received from the second plurality of combustionchambers to bypass the turbine.

In yet another aspect, the disclosure is directed toward a power system.The power system may include an engine having a first plurality ofcombustion chambers and a second plurality of combustion chambers. Thepower system may also include a first exhaust manifold configured toreceive exhaust from only the first plurality of combustion chambers, asecond exhaust manifold configured to receive exhaust from only thesecond plurality of combustion chambers, and a turbocharger. Theturbocharger may have a first volute in fluid communication with thefirst exhaust manifold, a second volute having a greater flow capacitythan the first volute and being in fluid communication with the secondexhaust manifold, a turbine wheel configured to receive exhaust from thefirst and second volutes, and a common outlet. The power system mayfurther include a valve assembly configured to selectively fluidlycommunicate the first volute with the second volute at a locationupstream of the turbine wheel, and to selectively fluidly communicatethe second volute with the common outlet to bypass the turbine wheel anda single actuator configured to move the valve assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic illustration of an exemplary disclosed powersystem;

FIG. 2 is a pictorial illustration of an exemplary disclosedturbocharger that may be used with the power system of FIG. 1;

FIG. 3 is a pictorial illustration of a portion of the turbochargershown in FIG. 2;

FIG. 4 is a pictorial illustration of a portion of the turbochargershown in FIG. 2;

FIG. 5 is a pictorial illustration of another exemplary disclosed powersystem;

FIG. 6 is a pictorial illustration of an exemplary disclosedturbocharger that may be used with the power system of FIG. 5;

FIG. 7 is a pictorial illustration of a portion of the turbochargershown in FIG. 6; and

FIG. 8 is a pictorial illustration of a portion of the turbochargershown in FIG. 6.

DETAILED DESCRIPTION

FIG. 1 illustrates a power system 10 having a power source 12, an airinduction system 14, and an exhaust system 16. For the purposes of thisdisclosure, power source 12 is depicted and described as a four-strokediesel engine. One skilled in the art will recognize, however, thatpower source 12 may be any other type of combustion engine such as, forexample, a gasoline or a gaseous fuel-powered engine. Power source 12may include an engine block 18 that at least partially defines aplurality of cylinders 20. A piston (not shown) may be slidably disposedwithin each cylinder 20 to reciprocate between a top-dead-centerposition and a bottom-dead-center position, and a cylinder head (notshown) may be associated with each cylinder 20. Cylinder 20, the piston,and the cylinder head may form a combustion chamber 22. In theillustrated embodiment, power source 12 includes six such combustionchambers 22. However, it is contemplated that power source 12 mayinclude a greater or lesser number of combustion chambers 22 and thatcombustion chambers 22 may be disposed in an “in-line” configuration, a“V” configuration, or in any other suitable configuration.

Air induction system 14 may include components configured to introducecharged air into power source 12. For example, air induction system 14may include an induction valve 24, one or more compressors 26, and anair cooler 28. Induction valve 24 may be connected upstream ofcompressor 26 via a fluid passageway 30 and configured to regulate aflow of atmospheric air to power source 12. Compressor 26 may embody afixed geometry compressor configured to receive air from induction valve24 and compress the air to a predetermined pressure level before itenters power source 12. Compressor 26 may be connected to power source12 via a fluid passageway 32. Air cooler 28 may be disposed within fluidpassageway 32, between power source 12 and compressor 26 and embody, forexample, an air-to-air heat exchanger, an air-to-liquid heat exchanger,or a combination of both to facilitate the transfer of thermal energy toor from the compressed air directed into power source 12.

Exhaust system 16 may include components configured to direct exhaustfrom power source 12 to the atmosphere. Specifically, exhaust system 16may include first and second exhaust manifolds 34 and 36 in fluidcommunication with combustion chambers 22, an exhaust gas recirculation(EGR) circuit 38 fluidly communicating first exhaust manifold 34 withair induction system 14, a turbine 40 associated with first and secondexhaust manifolds 34, 36, and a control system 44 for regulating exhaustflows from exhaust system 16 to air induction system 14. It iscontemplated that exhaust system 16 may include components in additionto those listed above such as, for example, particulate removingdevices, constituent absorbers or reducers, and attenuation devices, ifdesired.

Exhaust produced during the combustion process within combustionchambers 22 may exit power source 12 via either first exhaust manifold34 or second exhaust manifold 36. First exhaust manifold 34 may fluidlyconnect a first plurality of combustion chambers 22 of power source 12(e.g., the first three combustion chambers 22 from the right shown inFIG. 1) to turbine 40. Second exhaust manifold 36 may fluidly connect asecond plurality of combustion chambers 22 of power source 12 (e.g., thefinal three combustion chambers from the right shown in FIG. 1) toturbine 40.

EGR circuit 38 may include components that cooperate to redirect aportion of the exhaust produced by power source 12 from first exhaustmanifold 34 to air induction system 14. Specifically, EGR circuit 38 mayinclude an inlet port 52, an EGR cooler 54, a recirculation controlvalve 56, and a discharge port 58. Inlet port 52 may be fluidlyconnected to first exhaust manifold 34 upstream of turbine 40 andfluidly connected to EGR cooler 54 via a fluid passageway 60. Dischargeport 58 may receive exhaust from EGR cooler 54 via a fluid passageway62, and discharge the exhaust to air induction system 14 at a locationdownstream of air cooler 28. Recirculation control valve 56 may bedisposed within fluid passageway 62, between EGR cooler 54 and dischargeport 58. It is contemplated that a check valve, for example a reed-typecheck valve 50 may be situated within fluid passageway 62 upstream ordownstream of recirculation control valve 56 at a location where exhaustmixes with inlet air to provide for a unidirectional flow of exhaustthrough EGR circuit 38 (i.e., to inhibit bidirectional exhaust flowsthrough EGR circuit 38), if desired.

Recirculation control valve 56 may be located to control the flow ofexhaust recirculated through EGR circuit 38. Recirculation control valve56 may be any type of valve known in the art such as, for example, abutterfly valve, a diaphragm valve, a gate valve, a ball valve, a poppetvalve, or a globe valve. In addition, recirculation control valve 56 maybe solenoid-actuated, hydraulically-actuated, pneumatically-actuated oractuated in any other manner to selectively restrict or completely blockthe flow of exhaust through fluid passageways 60 and 62.

EGR cooler 54 may be configured to cool exhaust flowing through EGRcircuit 38 and, subsequently, components within EGR circuit 38 (e.g.,recirculation control valve 56). EGR cooler 54 may include aliquid-to-air heat exchanger, an air-to-air heat exchanger, or any othertype of heat exchanger known in the art for cooling an exhaust flow.

Turbine 40 may be a fixed geometry turbine configured to drivecompressor 26. For example, turbine 40 may be directly and mechanicallyconnected to compressor 26 by way of a shaft 64 to form a fixed geometryturbocharger 66. As the hot exhaust gases exiting power source 12 movethrough turbine 40 and expand against blades (not shown) therein,turbine 40 may rotate and drive the connected compressor 26 topressurize inlet air.

Turbine 40 may include a divided housing having a first volute 76 with afirst inlet 78 fluidly connected with first exhaust manifold 34, and asecond volute 80 with a second inlet 82 fluidly connected with secondexhaust manifold 36 (i.e., turbocharger 66 may have dual volutes). Awall member 84 may divide first volute 76 from second volute 80. Itshould be understood that at least a part of first volute 76 and/orfirst inlet 78 may have a smaller cross-sectional area and/orarea/radius (A/R) ratio than second volute 80 and/or second inlet 82.The smaller cross-sectional area or A/R ratio may help restrict the flowof exhaust through first exhaust manifold 34, thereby creatingbackpressure sufficient to push at least a portion of the exhaust fromfirst exhaust manifold 34 through EGR circuit 38.

A valve assembly 86 may be associated with turbine 40 to regulate apressure of exhaust within EGR circuit 38. Valve assembly 86 mayinclude, among other things, a balance valve 88, a wastegate valve 90,and a common actuator 92. Balance valve 88 may be configured toselectively allow exhaust from first volute 76 to pass to second volute80. Wastegate valve 90 may be configured to selectively allow exhaustfrom second volute 80 to bypass a turbine wheel 93 of turbine 40. Commonactuator 92 may be controlled to move both balance valve 88 andwastegate valve 90 between flow passing and flow blocking positions.Valve assembly 86 may be integral with turbine 40 and at least partiallyenclosed by a valve housing 94 that mounts to a turbine housing 96 ofturbine 40.

Balance valve 88 may be configured to regulate a pressure of exhaustwithin first exhaust manifold 34 by selectively allowing exhaust to flowfrom first volute 76 to second volute 80. It should be understood thatthe pressure within first exhaust manifold 34 may affect the amount ofexhaust pushed through EGR circuit 38. That is, when exhaust flows fromfirst volute 76 to second volute 80 by way of balance valve 88, apressure within first exhaust manifold 34 may be reduced and, as aresult of this reduction, an amount of exhaust forced from first exhaustmanifold 34 through EGR circuit 38 may be reduced by a proportionalamount. It should also be noted that, because exhaust may selectively beallowed to flow from first volute 76 to second volute 80 by way ofbalance valve 88, a pressure differential between first and secondvolutes 76 and 80 may be minimized, thereby minimizing an impact thispressure differential may have on turbocharger efficiency.

As shown in FIG. 2, balance valve 88 may be fixedly connected to commonactuator 92. Specifically, balance valve 88 may include a valve member98 having a pivot axis 100. A pivot member 102 may be fixedly connectedat a center thereof to valve member 98, and at an end thereof to commonactuator 92. In this configuration, as common actuator 92 moves linearlyin the direction of an arrow 104, pivot member 102 and connected valvemember 98 may both be caused to rotate together about pivot axis 100.

As illustrated in FIGS. 3 and 4, valve housing 94 may at least partiallydefine a fluid chamber 106 divided into two compartments 106 a and 106 bby a wall member 108. Compartment 106 a may fluidly communicate withfirst volute 76, while compartment 106 b may fluidly communicate withsecond volute 80. A port 110 within wall member 108 may fluidly connectcompartments 106 a and 106 b, and a sealing element 111 of valve member98 may selectively pivot about pivot axis 100 to open or close port 110and thereby selectively restrict a flow of exhaust from first volute 76to second volute 80 by way of port 110.

Referring back to FIG. 2, wastegate valve 90 may be connected to balancevalve 88 and to common actuator 92 by way of a link member 112. Inparticular, a pivot member 114 may be connected at one end thereof to avalve member 115 of wastegate valve 90, and include a protrusion 114 aat an opposing end thereof. Link member 112 may be fixedly connected toan end of pivot member 102, opposite the connection of pivot member 102to common actuator 92, and include a channel 112 a configured toslidingly receive protrusion 114 a of pivot member 114. In thisconfiguration, as balance valve 88 and pivot member 102 are rotatedabout pivot axis 100 by linear movement of common actuator 92, linkmember 112 may also move linearly in a direction substantially oppositethe movement of common actuator 92. And, as link member 112 moveslinearly, protrusion 114 a may be caused to slide within channel 112 aof link member 112 until an end of channel 112 a is engaged. Once theend of channel 112 a is engaged by protrusion 114 a, pivot member 114and connected valve member 115 may then be rotated about an axis 116together with pivot member 102 and connected valve member 98 about pivotaxis 100 by further movement of common actuator 92 in the samedirection. When common actuator 92 moves in a reverse direction, balancevalve 88 may again move first (i.e., before movement of wastegate valve90 is initiated) until an opposing end of channel 112 a is engaged byprotrusion 114 a.

Referring again to FIGS. 3 and 4, fluid chamber 106 may be separatedfrom a common outlet 118 of turbine 40 by a wall member 120. A port 122within wall member 120 may connect fluid chamber 106 with common outlet118, and a sealing element 124 of valve member 115 may selectively pivotabout axis 116 to open or close port 122 and thereby restrict a flow ofexhaust from second volute 80 to outlet 118 (i.e., sealing element 124may selectively allow or restrict exhaust within second volute 80 frombypassing turbine wheel 93 of turbine 40).

Referring again to FIG. 2, common actuator 92 may be pneumaticallyoperated to initiate movement of balance valve 88 and wastegate valve90. Specifically, common actuator 92 may include a spring-biased pistonmember (not shown) disposed within a pressure chamber 92 a and fixedlyconnected to a piston rod 92 b. Pressurized air directed into pressurechamber 92 a may urge the spring-biased piston member from a firstposition away from pressure chamber 92 a toward a second position.Conversely, allowing the pressurized air to drain from pressure chamber92 a may return the spring-biased piston member to the first position.As piston rod 92 b translates between the first and second positions,balance valve 88 may first move, followed by movement of wastegate valve90. It is contemplated that common actuator 92 may alternatively bemechanically operated, hydraulically operated, electrically operated, oroperated in any other suitable manner. It is also contemplated thatpiston rod 92 b may be moved to any position between the first andsecond positions to thereby provide more than two levels of actuation,if desired (i.e., common actuator 92 may be a proportional actuator,wherein a movement amount of piston rod 92 b is directly proportional toa pressure of the air directed into pressure chamber 92 a).

Referring back to FIG. 1, control system 44 may include components thatfunction to regulate the flow rate and pressure of exhaust passingthough first volute 76, second volute 80, and EGR circuit 38 byadjusting the position of recirculation control valve 56, balance valve88, and/or wastegate valve 90 in response to sensory input.Specifically, control system 44 may include a sensor 46, and acontroller 48 in communication with sensor 46, recirculation controlvalve 56, and common actuator 92. Based on signals received from sensor46, controller 48 may adjust a position of recirculation control valve56 and/or of common actuator 92 to vary the restrictions provided byrecirculation control valve 56, balance valve 88, and/or wastegate valve90.

Although shown as located downstream of EGR cooler 54 and upstream ofrecirculation control valve 56, sensor 46 may alternatively be locatedanywhere within EGR circuit 38 and embody, for example, a mass air flowsensor such as a hot wire anemometer or a venturi-type sensor configuredto sense pressure and/or a flow rate of exhaust passing through EGRcircuit 38. Controller 48 may use signals produced by sensor 46 todetermine and/or adjust a backpressure within first exhaust manifold 34such that a desired amount of exhaust is recirculated back into powersource 12 for subsequent combustion. This adjustment of pressure will befurther explained in more detail below.

Controller 48 may embody a single or multiple microprocessors, fieldprogrammable gate arrays (FPGAs), digital signal processors (DSPs), etc.that include a means for controlling an operation of power system 10 inresponse to signals received from sensor 46. Numerous commerciallyavailable microprocessors can be configured to perform the functions ofcontroller 48. It should be appreciated that controller 48 could readilyembody a microprocessor separate from that controlling other non-exhaustrelated power system functions, or that controller 48 could be integralwith a general power system microprocessor and be capable of controllingnumerous power system functions and modes of operation. If separate froma general power system microprocessor, controller 48 may communicatewith the general power system microprocessor via data links or othermethods. Various other known circuits may be associated with controller48, including power supply circuitry, signal-conditioning circuitry,actuator driver circuitry (i.e., circuitry powering solenoids, motors,or piezo actuators), communication circuitry, and other appropriatecircuitry.

Before regulating the flow of exhaust through EGR circuit 38, controller48 may first receive data indicative of an operational condition ofpower source 12 or a desired exhaust flow rate and/or pressure. Suchdata may be received from another controller or computer (not shown). Inan alternative embodiment, operational condition data may be receivedfrom sensors strategically located throughout power system 10.Controller 48 may then utilize stored algorithms, equations,subroutines, look-up maps, and/or tables to analyze the operationalcondition data and determine a corresponding desired exhaust pressureand/or flow rate through EGR circuit 38.

Controller 48 may also receive signals from sensor 46 indicative of theflow rate or pressure of exhaust flowing through first exhaust manifold34. Upon receiving input signals from sensor 46, controller 48 mayperform a plurality of operations utilizing stored algorithms,equations, subroutines, look-up maps and/or tables to determine whetherthe flow rate or pressure of exhaust flowing through first exhaustmanifold 34 is within a desired range for producing the desired exhaustflow rate through EGR circuit 38. In an alternate embodiment, it iscontemplated that controller 48 may receive signals from various sensors(not shown) located throughout exhaust system 16 and/or power system 10instead of sensor 46. Such sensors may sense parameters that may be usedto calculate the flow rate or pressure of exhaust flowing through firstexhaust manifold 34, if desired.

Based on the comparison of the actual EGR flow rate and/or pressure withthe desired range of flow rates and/or pressures, controller 48 mayadjust operation of exhaust system 16. That is, controller 48 may adjustoperation of recirculation control valve 56, of balance valve 88, and/orof wastegate valve 90 to affect the pressure within first exhaustmanifold 34 and the resulting flow rates of exhaust through EGR circuit38, first volute 76, and second volute 80. To increase the flow rate andpressure of exhaust passing through first volute 76 and EGR circuit 38,and to simultaneously decrease the flow rates and pressures of exhaustpassing through second volute 80, balance valve 88 may be closed to agreater extent. To decrease the flow rate and pressure of exhaustpassing through first volute 76 and EGR circuit 38, and tosimultaneously increase the flow rates and pressures of exhaust passingthrough second volute 80, balance valve 88 may be opened. Recirculationcontrol valve 56 may be opened to increase an EGR flow rate and decreaseexhaust flow through first volute 76, and closed to decrease an EGR flowrate and increase exhaust flow through first volute 76. In oneembodiment, controller 48 may primarily adjust operation of balancevalve 88 to achieve a desired flow rate and/or pressure of exhaustthrough EGR circuit 38. After balance valve 88 has been adjusted to amaximum or minimum position, controller 48 may then adjust operation ofrecirculation control valve 56 and/or wastegate valve 90 to providefurther EGR modulation.

FIG. 5 illustrates an alternative embodiment of power system 10. Similarto the embodiment of FIG. 1, the embodiment of FIG. 5 includes powersystem 10 having power source 12, air induction system 14, and exhaustsystem 16. However, in contrast to the embodiment of FIG. 1, turbine 40of exhaust system 16 may include a different valve assembly 86. That is,valve assembly 86 of FIG. 5 may include a balance valve 126 and awastegate valve 128 moved by common actuator 92. Balance valve 126 mayinclude two separate valve members, and wastegate valve 128 may have adifferent configuration than in the previous embodiments. In addition,the linkage connecting balance valve 126 and wastegate valve 128 tocommon actuator 92 may be different, as will be described in more detailbelow.

Balance valve 126 and wastegate valve 128 may connect to and be moved bycommon actuator 92 in a manner similar to the embodiments of FIGS. 1-5.That is, as illustrated in FIG. 6, balance valve 126 may be fixedlyconnected to common actuator 92 by way of a pivot member 130 to rotateabout a pivot axis 132. Wastegate valve 128 may include a pivot member134 having a channel 134 a. And, as common actuator 92 begins to movelinearly, only pivot member 130 and connected balance valve 126 may moveuntil a protrusion 130 a of pivot member 130 engages an end of channel134 a. Once protrusion 130 a engages the end of channel 134 a, pivotmember 134 and connected wastegate valve 128 may also be moved by thelinear motion of common actuator 92.

As shown in FIGS. 7 and 8, balance valve 126 may include a first valvemember 136 and a second valve member 138 rigidly connected to each otherand disposed at least partially within a fluid chamber 140. Fluidchamber 140 may be at least partially defined by turbine housing 96(i.e., at least partially defined by a wall member 141 of turbinehousing 96) and fluidly communicate with fluid chamber 106 of valvehousing 94. No walls may separate fluid chambers 140 or 106 intoseparate compartments in this embodiment. First valve member 136 may beassociated with first volute 76, while second valve member 138 may beassociated with second volute 80. A first port 142 within wall member141 may communicate fluid chamber 140 with first volute 76, while asecond port 144 within wall member 141 may fluidly communicate fluidchamber 140 with second volute 80. First and second valve members 136,138 may include first and second sealing surfaces (not shown),respectively, that are configured to selectively restrict fluid flowthrough first and second ports 142, 144. Both of first and second valvemembers 136, 138 may be connected to a rod member 146 to rotate togetherabout pivot axis 132 when an input from common actuator 92 is received.

In the embodiment of FIGS. 5-8, wastegate valve 128 may be substantiallyaxially aligned with balance valve 126 and include a sleeve member 148fixedly connected to pivot member 126 and configured to at leastpartially receive rod member 146 of balance valve 126. A valve member150 of wastegate valve 128 may be rigidly connected to rotate withsleeve member 148 and selectively restrict exhaust flow through a port152 to common outlet 118 of turbine 40.

INDUSTRIAL APPLICABILITY

The disclosed exhaust system may be implemented into any power systemapplication where charged air induction and exhaust gas recirculationare utilized. The disclosed exhaust system may be simple, have highdurability, and offer control precision. Specifically, the fixedgeometry nature of turbocharger 66 may decrease the complexity and costof the disclosed exhaust system, while recirculation control valve 56,balance valves 88 or 126, and wastegate valves 90 or 128 may help tomaintain precision and controllability: In addition, the location ofrecirculation control valve 56, sensor 46, and check valve 50 downstreamof EGR cooler 54 may result in cooler operating temperatures of thosecomponents and extended component lives. Further, the use of check valve50 may enhance turbocharger stability and efficiency. Finally, byutilizing direct flow sensing and feedback control, precise regulationof exhaust gas recirculation may be possible.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed turbocharger.Other embodiments will be apparent to those skilled in the art fromconsideration of the specification and practice of the disclosedturbocharger. It is intended that the specification and examples beconsidered as exemplary only, with a true scope being indicated by thefollowing claims and their equivalents.

1. A turbocharger, comprising: a turbine housing having a first volute,a second volute, and a common outlet; a turbine wheel disposed betweenthe common outlet and the first and second volutes; a first valveconfigured to selectively fluidly communicate the first volute with thesecond volute upstream of the turbine wheel; a second valve configuredto selectively fluidly communicate the second volute with the commonoutlet to bypass the turbine wheel; a common actuator configured to movethe first and second valves; and a first wall fluidly separating thefirst volute from the second volute, the first wall having a first port,the first valve being configured to selectively block the first port. 2.The turbocharger of claim 1, wherein the first and second valves areconfigured to rotate, and the common actuator is configured to movelinearly.
 3. The turbocharger of claim 2, wherein the common actuator isconfigured to move in a first direction by a first amount to rotate onlythe first valve, and the common actuator is configured to move in thefirst direction by a second amount to rotate both the first valve andthe second valve.
 4. The turbocharger of claim 1, wherein the commonactuator is pneumatically operated.
 5. The turbocharger of claim 1,further including a valve housing connected to the turbine housing to atleast partially enclose the first and second valves, the valve housingincluding the first wall.
 6. (canceled)
 7. The turbocharger of claim 1,wherein the common actuator is fixedly connected to only the firstvalve.
 8. The turbocharger of claim 7, further including: a first pivotmember fixedly connecting the common actuator to the first valve; asecond pivot member fixedly connected to only the second valve; and alink member fixedly connected to the first pivot member and including achannel configured to slidingly receive the second pivot member. 9.(canceled)
 10. The turbocharger of claim 1, wherein the common actuatoris configured to move to permit the first valve to fluidly communicatethe first volute with the second volute before the second valve fluidlycommunicates the second volute with the common outlet.
 11. Theturbocharger of claim 1, wherein the first valve includes a first pivotaxis, and the second valve includes a second pivot axis offset from thefirst pivot axis.
 12. (canceled)
 13. (canceled)
 14. The turbocharger ofclaim 1, further including: a second wall fluidly separating the secondvolute from the common outlet, the second wall having a second port,wherein: the second valve is configured to selectively block the secondport. 15.-17. (canceled)
 18. A method of handling exhaust from an enginehaving a first plurality of combustion chambers and a second pluralityof combustion chambers, the method comprising: receiving exhaust fromthe first plurality of combustion chambers; receiving exhaust from thesecond plurality of combustion chambers; directing exhaust received fromthe first and second pluralities of combustion chambers through aturbine, the turbine including a housing having a first volute and asecond volute; moving a common actuator in a first direction by a firstamount to actuate a first valve of a valve assembly to open a firstport, thereby mixing exhaust received from the first plurality ofcombustion chambers with exhaust received from the second plurality ofcombustion chambers, the first port being provided in a first wallfluidly separating the first volute from the second volute; and movingthe common actuator in the first direction by a second amount to actuatea second valve of the valve assembly to open a second port, therebyallowing exhaust received from the second plurality of combustionchambers to bypass the turbine, the second port being provided in asecond wall fluidly separating the second volute from a common outlet ofthe turbine.
 19. The method of claim 18, further including convertinglinear motion from a common actuator to rotation of the valve assembly.20. A power system, comprising: an engine having a first plurality ofcombustion chambers and a second plurality of combustion chambers; afirst exhaust manifold configured to receive exhaust from only the firstplurality of combustion chambers; a second exhaust manifold configuredto receive exhaust from only the second plurality of combustionchambers; a turbocharger having: a turbine housing, the turbine housingincluding a first volute in fluid communication with the first exhaustmanifold, a second volute having a greater flow capacity than the firstvolute and being in fluid communication with the second exhaustmanifold, and a common outlet, and a turbine wheel configured to receiveexhaust from the first and second volutes; a valve assembly including: afirst valve configured to selectively fluidly communicate the firstvolute with the second volute at a location upstream of the turbinewheel, and a second valve configured to selectively fluidly communicatethe second volute with the common outlet to bypass the turbine wheel; asingle actuator configured to move the valve assembly; and a valvehousing connected to the turbine housing and at least partiallyenclosing the first and second valves, the valve housing including: afirst wall member separating a first compartment fluidly communicatingwith the first volute from a second compartment fluidly communicatingwith the second volute, and a second wall member separating the secondcompartment from the common outlet, the first valve being provided inthe first compartment between the first and second walls.
 21. The powersystem of claim 20, wherein the first valve includes a first pivot axis,and the second valve includes a second pivot axis offset from the firstpivot axis.
 22. The power system of claim 20, wherein the first andsecond wall members are substantially parallel.
 23. The power system ofclaim 20, wherein the first valve is disposed between the first andsecond wall members.
 24. The method of claim 18, wherein, prior tomoving the common actuator in the first direction, the first valvecloses the first port and the second valve closes the second port. 25.The method of claim 18, wherein the second amount of movement of thecommon actuator is greater than the first amount of movement of thecommon actuator.
 26. The turbocharger of claim 14, further including avalve housing connected to the turbine housing to at least partiallyenclose the first and second valves, the valve housing including thefirst wall and the second wall.